- Isaac Israeli ben Joseph
Isaac Israeli ben Joseph or Yitzhak ben Yosef (often known as Isaac Israeli the Younger) was a Spanish-Jewish
astronomer /astrologer who flourished at Toledo in the first half of the fourteenth century. He was a pupil ofAsher ben Yehiel , at whose request (in 1310) he wrote the astronomical work "Yesod Olam", the best contribution on that subject toHebrew literature . It treats ofgeometry andtrigonometry as introductory to the subject-matter; of the structure and position of the globe; of the number and movements of thecelestial spheres ; of the time differences in days and nights in the various parts of the earth; of the movements of sun and moon; of thesolstice s, the "neomeniæ", theeclipse s, and the leap-years; it contains as well astronomical tables (anephemeris ) and aperpetual calendar . It also deals (iv, § 17) with the chronological systems of other nations and religions, especiallyChristianity ; and gives (iv, § 18) in chronological order the noted personages of theBiblical ,Talmud ic, and geonic periods, following the "Sefer ha-Qabbalah " ofAbraham ibn Daud . This last was included byZacuto in his "Sefer ha-Yuḥasin."The "Yesod Olam" was first published at Berlin, in 1777, by
Jacob Shklower . A more complete edition, with a preface by David Cassel, was published by B. Goldberg and L. Rosenkranz (1848). Israeli's work was much studied in theMiddle Ages .Isaac al-Hadib ,Judah Bassan , andElijah Mizrahi annotated it, and an anonymous author wrote a commentary to it (Neubauer, "Cat. Bodl. Hebr. MSS." Nos. 2044, 746, 5). An abridgment was made inArabic by the author's sonJoseph Israeli ben Isaac , of which the Hebrew translation, "Kitzur Yesod Olam" is still extant (ib. No. 1319, 6).Israeli was also the author of two other astronomical works, "Sha'ar ha-Shamayim" and "Sha'ar ha-Milu'im," both extant in manuscript (ib. No. 2046).
References
*De Rossi, Dizionario, p. 130;
*Cassel, preface to Yesod 'Olam;
*Eliakim Carmoly , Itinéraires, p. 224;
*Steinschneider , Cat. Bodl. col. 1124;
*idem, Hebr. Uebers. p. 596;
*idem, Die Arabische Litteratur der Juden, § 121;
*Grätz , Gesch. vii. 249.
*JewishEncyclopedia
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